Tube Type Heat Exchanger Research Articles

English

Generally, 35-40% of the heat exchangers used in industries are shell and tube heat exchanger. Here an experiment on shell and tube type heat exchanger is conducted. There are problems like scaling, fouling, welding defects and maintenance cost. In this experiment, design of shell and tube type heat exchanger baffle is changed. Considering this design as the basis, effectiveness of shell and tube type heat exchanger is measured. Performance in terms of effectiveness is firstly measured for normal flat baffle having 3:2 cutting ratio. Then performance in terms of effectiveness is measured for helical baffle. After measuring the performance for both types of baffle, results of both experiments are compared. Also the turbulence gained due to helical baffle helps to reduce the fouling effect in the heat exchanger.

Effect of Segmental Baffles at Different Orientation on the Performances of Single Pass Shell and Tube Heat Exchanger

In present work, experimentation of single pass, counter flow shell and tube heat exchanger containing segmental baffles at different orientations has been conducted to calculate some parameters (heat transfer rate and pressure drop) at different Reynolds number in laminar flow. In the present work, an attempt has been made to study the effect of increase in Reynolds number at different angular orientation “θ” of the baffles. The range of “θ” vary from 0° to 45° (i.e 0°, 15°, 30° and 45°) and Reynolds number ranges from 500 to 2000 (i.e 500, 1000, 1500 and 2000). A prototype model of shell and tube type heat exchanger has been fabricated to carry out the experiments. The experiments were performed to determine the effect of baffle orientation on the performance of shell and tube heat exchanger. Water is taken as the working fluid used in both shell and tubes. The objective of the present work is to predict the variation of heat transfer rate, LMTD, heat transfer coefficient, and pressure drop to the shell side with change in range of Reynolds number at different baffle orientations. Based on the experimental result it has been observed that the angular orientation of baffles and the Reynolds number effects the heat transfer rate and pressure drop in the shell and tube heat exchanger. The heat transfer rate increases up to 30° angular orientation of the baffles and after that there is a drop in heat transfer rate at θ = 45°. The pressure drop to the shell sides decreases continuously from 0° to 45° which helps in reducing the pumping cost of the shell and tube heat exchanger.

Effect of the heat exchanger in the waste heat recovery system on a gasoline engine performance

In this paper, the effects of increasing the back pressure on the engine performance by using heat exchangers mounted in the exhaust line to recover waste heat from the engine exhaust are described. An experimental study was conducted with two different types of heat exchanger, namely shell-and-tube-type heat exchangers and fin-and tube-type heat exchangers. The heat exchanger increased the resistance of the engine exhaust through the exhaust line, and the engine back pressure increased to 16 kPa, which led to an increase in the brake specific fuel consumption by up to 3% depending on the operating conditions. The back pressure adversely affected the performance of the automotive engine combined with the Rankine cycle and thus caused the overall thermal efficiency of the system to deteriorate. Consequently, if the back-pressure effect was taken into account, the contribution of recovering heat from the engine exhaust to the improvement in the system efficiency was lower than expected.

냉장고용 판형 핀-관 응축기의 열전달 성능에 관한 실험적 연구

본 판형 핀-관형 응축기는 기존의 냉장고에 적용돼오던 원형 핀 콘덴서보다 약 30 % 정도 가벼운 무게를 갖는다. 가벼운 무게는 곧 재료비 줄임을 의미하기 때문에 동일한 성능만 구현된다면, 관련 산업발전에 큰 영향을 줄 수 있다. 이러한 판형-핀 열교환기가 적용된 가정용 냉장고 응축기의 실용화 가능성을 조사하기 위해 실험적인 연구가 수행된다. 실험평가에는 원래 적용돼오던 원형 핀-관 열교환기를 포함하여 총 네 가지 유형의 열교환기가 사용되며, 실제 가정용 냉장고와 비슷한 운전 상태를 제공하는 정교한 냉매공급 장치가 이용되고, 각 실험 시료에 대해 열전달율과 공기측 압력손실 등이 정밀하게 측정된다. 실험결과, 판형 핀-관 열교환기의 열전달 성능은 기존의 원형 핀-관 열교환기보다 13% 이상 작은 것으로 나타났으나, 공기측 유로압력손실이 작고 단위질량당 열전달률이 우수한 것으로 나타났으며, 공기유속 증가와 유로 변경과 같은 최적화에 의한 동일 성능 구현의 가능성을 보여주는 것으로 나타났다. A plate-fin tube type heat exchanger has a lighter weight, approximately 30%, than the conventional circular-fin type condenser of household refrigerator. Because the low weight means low cost, it can have significant effects on the growth of related businesses if similar performance can be guaranteed. To check the possibility of the use of such a plate fin-tube condenser, experimental evaluations were performed in this study. Four different condensers including a conventional circular fin-tube condenser were used for the test. A well designed refrigerant supply system was used to supply similar conditions with a refrigerator, and the heat transfer rate and pressure drops of air side were measured precisely. As a result, the plate fin-tube type condensers showed a lower heat transfer rate of more than 13% than the conventional circular fin-tube type condenser, but the air side pressure drop was reduced and the heat transfer per unit weight was increased. Therefore, it shows the possibility of the use of a plate fin-tube type condenser after optimizing the air flow path and increasing the air flow to make a similar heat transfer rate.

English

The present experimental study demonstrates the performance and emission characteristics of a single cylinder dual fuel diesel engine with producer gas as the primary fuel and diesel, preheated Jatropha oil and Jatropha oil methyl ester as injected fuels. In order to reduce the viscosity of Jatropha oil, a shell and tube type heat exchanger was designed and fabricated for preheating Jatropha oil using engine exhaust gas. The performance parameters, such as brake specific fuel consumption, brake thermal efficiency and exhaust gas temperature, have shown improved results with baseline diesel and producer gas, whereas the above parameters are very close to other test fuels under different loading conditions. All the emission parameters are found to be on the higher side for preheated oilcompared to diesel-producer gas dual fuel operation at all load conditions. With Jatropha oil methyl ester-producer gas dual fuel operation, however, emission parameters such as CO2, smoke and NOx are higher compared to diesel-producer gas operation. The smoke emission for preheated Jatropha oil-producer gas dual fuel operation is approximately 60% higher than that of diesel-producer gas operation at full load. From the present experimental investigation it may be concluded that alternative fuel combinations such as preheated Jatropha oil-producer gas and Jatropha oil methyl ester-producer gas can successfully replace diesel as the major fuel in diesel engines with little modification. The present paper also recommends further investigation to improve fuel properties and in-cylinder combustion phenomena of preheated Jatropha oil and its methyl ester before use in a diesel engine.

Improved performance of secondary heat exchanger for latent heat recovery from flue gas using mini-tubes

A new type of heat exchanger, in which flue gas flows inside thin tubes and cool water is on the shell-side, was proposed to develop the performance and compactness of shell and tube type heat exchangers for latent heat recovery from flue gas. The experimental heat transfer characteristics of single tubes were systematically investigated to determine the effects of tube diameter (1.0–5.0 mm) and length (7–100 mm). Furthermore, a correlation between the non-dimensional bulk mean temperature and the ratio of effective tube length to the thermal entrance region was proposed and was correlated well with the measurement data. Prediction of the heat exchanger performance using this correlation was possible. As a result, it was elucidated that the using mini-tubes is remarkably effective to reduce the size of heat exchanger due to enhancement of heat transfer coefficient and enlargement of heat transfer surface. The volume with 1 mm inner diameter of tubes was approximately 5 percent of that with 5 mm in diameter.

An experimental study on the pressure drop and heat transfer through straight and curved small diameter tubes

A tube type heat exchanger is often the only solution when minimum pressure loss is a requirement. In addition, small diameter tubes are preferable because of an increased heat transfer area within an acceptable pressure loss limit. The present work reports on both an analytic model and experimental results with regards to the pressure drop and heat transfer characteristics of compact straight, C-curved, and U-curved tubes. The inner diameter of the tube (D) for our selected heat exchanger type was 1.26 mm with a thickness of 0.12 mm and a total length of 150.8 D. For the experiment, pressurized nitrogen gas bottles were used rather than an air compressor system in order to simplify the test facility. Hence the pressure conditions were easily set at 10, 30, and 50 bar corresponding to a range of Reynolds numbers from 10000 to 50000. To elevate the air temperature outside the tube (from 100°C to 400°C), an electric furnace was installed around the “test tube”. An analytic model to determine the pressure loss through curved tubes-referred to as the modified friction factor- is proposed. Good agreement was found between the modified friction factor and existing correlations, thus confirming the suitability of this model for determining pressure losses for different shape of tubes. The average measured Nusselt numbers were within 10- 15% of the Dittus-Boelter and Gnielinski correlations.

Determination of Internal Pressure in a Shell and Tube Type of Heat Exchanger by Using IBR and ASME Codes

The shell and tube type heat exchanger is a non-fired pressure system consisting of two different pressure chambers such as shell chamber and tube chamber. It is separated by the internal tube wall, two media flow past each other with such alignment that, if there is a heat difference, they will mutually exchange heat without mixing in the process..While there is an enormous variety of specific design features that can be used in shell and tube exchangers, the number of basic components is relatively small. This paper aims at performing a comprehensive comparison of the design outputs by IBR and ASME codes of critical components of a shell and tube type heat exchanger in an attempt to show the redundancy in designing the components using both these codes simultaneously.

Performance Analysis of Shell & Tube Type Heat Exchanger under the Effect of Varied Operating Conditions

This paper consists of extensive thermal analysis of the effects of severe loading conditions on the performance of the heat exchanger. To serve the purpose a simplified model of shell and tube type heat exchanger has been designed using kern's method to cool the water from 55 to 45 by using water at room temperature. Then we have carried out steady state thermal analysis on ANSYS 14.0 to justify the design. After that the practical working model of the same has been fabricated using the components of the exact dimensions as derived from the designing. We have tested the heat exchanger under various flow conditions using the insulations of aluminium foil, cotton wool, tape, foam, paper etc. We have also tested the heat exchanger under various ambient temperatures to see its effect on the performance of the heat exchanger. Moreover we have tried to create the turbulence by closing the pump opening and observed its effect on its effectiveness. All these observations along with their discussions have been discussed in detail inside the paper.

Numerical Investigation of Internal Pressure in a shell and Tube type of Heat Exchanger by using FEA

Shell and Tube Heat Exchangers are one of the most popular types of exchanger in heat transfer applications. Due to the flexibility, the designer has to allow for a wide range of pressures and temperatures. They are widely used in petroleum refineries, chemical plants, petrochemical plants, natural gas processing, air-conditioning, refrigeration and automotive applications. It utilizes a bundle of tubes through which one of the fluids flows. These tubes are enclosed in a shell with provisions for the other fluid to flow through the spaces between the tubes. In most designs of this type, the free fluid flows roughly perpendicular to the tubes containing the other fluid, in what is known as a cross-flow exchange. In nuclear reactors fuel rods may replace the tubes, and the cooling fluid flowing around the rods removes the heat generated by the fission process.A comprehensive Finite Element Analysis (FEA) has been performed on the critical heat exchanger components in order to validate the results of the components designed using the prescribed codes. The computational analysis helps visualize the areas of high stress concentration thereby aiding the designer to identify the failure prone regions. The regions susceptible to failure can be suitably modified to safeguard against failure. This paper aims at performing a design outputs by IBR codes of critical components of a shell and tube type heat exchanger in an attempt to show the redundancy in designing the components. Furthermore FEA shown the values of stress getting developed in the components for given operating conditions are much lesser than the allowable values of stress for those respective material. Thus the components are safe against such loading.

On prediction of heat exchanger performance for latent heat recovery using flue gas

The new type heat exchanger, in which fuel gas flows inside thin tubes and water is shell-side, was proposed to develop the performance and compactness of shell & tube type heat exchanger for latent heat recovery from flue gas. The effects of tube diameter (1.0~5.0 mm) and heat exchanging length (7~100 mm) on the heat transfer characteristics of a single tube were systematically investigated. Moreover, the variations of gas inlet temperature or velocity conditions are studied considering the diverse usage of the gas water heater. It was shown that the usage of thinner tubes was remarkably effective to achieve high performance. That is, since the steep temperature drop near inlet occurred and high heat transfer rate was realized for thinner tubes of 1.0mm and 2.0mm in inner diameter compared with thicker tubes. In addition, the increase in the volumetric heat transfer area in thin tube type heat exchanger contributed to the compactness. Furthermore, the non-dimensional correlations concerning non-dimensional bulk mean temperature and specific enthalpy are proposed by using the ratio of effective tube length and thermal entrance region and correlate well with the measurement data regardless of diameter or inlet conditions. It is possible to predict the heat exchanger performance by using the correlations. As a result, it was elucidated that the using mini-tubes is remarkably effective to reduce the size of heat exchanger. For example, the volume with 1 mm inner diameter of tubes is approximately 4 percent of that with 5 mm in diameter.

Performance evaluation of multi-effect distiller for optimized solar thermal desalination

In this study we have carried out a performance evaluation on a recently developed multi-effect distiller with a 3 m3/day capacity and Shell & Tube type heat exchanger, which has been optimized for solar thermal desalination systems in order to increase mechanical efficiency and economical efficiency. Also, the effective heat transfer of Shell & Tube heat exchanger was used in Cu (90%) – NI (10%) corrugated tube.The parameters relating to the performance of multi effect distillation are known as hot water flow rate. The experimental conditions for each parameters were 18 °C for seawater inlet temperature, 6 m3/h seawater inlet volume flow rate, 75 °C for hot water inlet temperature, 2.4, 3.6, and 4.8 m3/h for hot water inlet volume flow rate, respectively.The results are as follows, development for multi effect distillation was required about 40 kW heat and 35 kW cooling source to produce 3 m3/day of fresh water. And, performance ratio of development multi effect distillation was about 2.0191.

핀튜브형 흡착탑에서 열 및 물질전달 수치해석

Nowadays, adsorption chillers have been receiving considerable attention, as they are energy saving and environmentally benign systems. A fin tube type heat exchanger in which adsorption/desorption takes place is required with more compact size. The adsorption chiller is expected to have high energy efficiency in utilizing the waste heat exhausted from a process. The objectives of this paper are to scrutinize the effect of design parameters on the adsorption performance, especially the fin pitch of the fin tube, and to develop an optimal design fin tube heat exchanger in a silica gel/water adsorption chiller. From the numerical results, the fin pitch of 2.5 mm shows the highest adsorption rate, compared to other fin pitches, such as 5 mm, 7.5 mm and 10mm. Also, the adsorption rate is affected by the cooling water and hot water temperature.

English

Heat transfer augmentation techniques refer to different methods used to increase rate of heat transfer without affecting much overall performance of the system. These techniques are used in heat exchangers. Like ribs, jet impingement and other passive heat transfer enhancement methods, insertion of baffle in a cooling system has been used for various types of industrial applications such as internal cooling systems of gas turbine blades, electronic cooling devices, shell and tube type heat exchangers, thermal regenerators and labyrinth seals for turbo-machines. These techniques broadly are of three types namely: passive, active and compound techniques. This paper reviews the internal cooling augmentation using different type of baffles. Key words: Heat transfer augmentation technique, baffles, active method, passive method, compound method.

관형 열교환기의 기계적 건전성 확보를 위한 유체-고체 연성해석과 브레이징 접합부의 국부적 물성분포 분석

최근 환경적 요인으로 친환경 에너지나 효율성이 높은 에너지관리 기술에 관한 많은 연구가 진행되고 있다. 그 중에서 열교환기는 역사가 오래된 기계장치 이지만 최근 온실가스 저감을 위해 항공기 등에 응용을 시도함에 따라 그 가치가 증가하고 있다. 또한 이러한 열교환기가 항공기 엔진에 적용될 경우 고온, 고압의 조건을 견디어야 함으로 기계적 건전성 평가는 매우 중요하다. 따라서 본 연구에서는 관형 열교환기의 취약부인 브레이징 접합부의 국부적인 물성분포 분석과 유체-고체 연성해석을 통하여 구조적 안전성을 평가하였다. U자형 단일 곡관을 제작하여 해석과 실험을 통하여 신뢰성을 검증하였고 브레이징 조건 변경을 통하여 재료 분포를 확인하였다.

Evaluation of mechanical integrity on the brazing joint of a tube-type heat exchanger with considering local material properties

Recently, the demands for eco-friendly and effective energy systems have rapidly increased due to global environment problems. A heat exchanger is a well-known mechanical rig that has been used for a long time in many energy systems to reduce heat energy loss and to increase energy efficiency. However, till now, there have been few attempts to install a heat exchanger inside of an airliner engine. In such a case, the heat exchanger should be designed to be compact, lightweight, and highly reliable; therefore, the issue of the mechanical integrity of the heat exchanger becomes very important. In this study, we suggest a method by which it is possible to evaluate the mechanical integrity of a tube-type heat exchanger using global and local analysis. In the global analysis, fluid–structure interaction was introduced to get global behavior of a tube, which was used as boundary conditions in the local analysis. Also, local material properties near a brazing joint were measured using a nano-indentation test, and then they were utilized in the local analysis to evaluate clearly stress distribution around the joint. Through this study, a U-shaped single tube brazed on a manifold, which is a segment of a tube-type heat exchanger, was used as an example; its fatigue limit and stress concentration on the joint depending on the change of fillet radius were estimated by the proposed approach.

DESIGN AND EXPERIMENTAL ANALYSIS OF CONDENSER FOR THE PRODUCTION OF BAMBOO VINEGAR

This paper presents methods for the production of Bamboo Vinegar. Bamboo Vinegar is formed on condensation of Bamboo Vapor which is a byproduct of bamboo pyrolysis occurring during the process of production of Bamboo Charcoal. The Paper mentions the conventional practices of producing Bamboo Vinegar and provides detailed study on the development of a condenser of adequate rating and sizing for the production of Bamboo Vinegar. Appropriate assumptions are made in designing the condenser which is a modification of a shell and tube type heat exchanger. The condenser acts as a heat sink improving the yield and quality of bamboo vinegar produced. Designs have been attempted with strong consideration for manufacture and operational cost as the condenser finds application amongst rural people with little or no technical knowhow, therefore simplicity of design is absolutely critical. Experimental results confirm working prototype of condensation system. Improvement over conventional method of production is specified for in this paper.

High Temperature Design and Damage Evaluation of MOD.9Cr-1Mo Steel Heat Exchanger

High temperature design and evaluation of creep-fatigue damage for sodium-to-sodium heat exchanger, decay heat exchanger (DHX), in a sodium test loop have been conducted. The DHX is a shell- and tube-type heat exchanger with an outer diameter of 21.7 mm and effective length of 1.73 m. The DHX shell and tube materials were Mod.9Cr-1Mo steel. The temperatures of shell inlet and shell outlet in the DHX are 510 °C and 308 °C, respectively, while the temperatures of tube inlet and outlet are 254 °C and 475 °C, respectively. Three-dimensional finite element analysis was conducted for the DHX, and evaluation of creep-fatigue damage at several critical locations of the heat exchanger was carried out according to the elevated temperature design codes of the ASME Section III Subsection NH and RCC-MR. Evaluations on the integrity of the DHX and code comparisons were carried out for the critical locations of the DHX. The evaluation results showed that damages at the tubesheet joints of tube-to-tubesheet and tubesheet-to-shell were not so critical in the present DHX model.

수직형 순환유동층 열교환기에서의 유체유동과 온도장의 수치해석

The numerical analysis by using CFX 11.0 commercial code was done for prediction of fluid flow and thermal field in the vertical heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the fluid flow and temperatures in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which the solid particles of glasses (3 <TEX>$mm{\Phi}$</TEX>) were used in the fluidized bed with a smooth tube. The effect of circulation on the distance(L) of tube inlet and baffle plate was also examined. The present experimental and numerical results showed that the particles in the distance (Ds) of 15 mm showed a more efficient circulation without stacked the space and the LMTD(Log Mean Temperature Difference) in the fluidized bed type was much lower than that in the typical type shell and tube heat exchanger.

Creep-fatigue damage evaluation of sodium to air heat exchanger in sodium test loop facility

A high temperature design and evaluation of creep-fatigue damage for a sodium-to-air heat exchanger, AHX, has been conducted according to the recent versions of the high temperature design codes based on a full three-dimensional finite element analysis. AHX is a shell- and tube-type heat exchanger with 36 helical tubes, and has an outer diameter of 1.59m and height of 6.5m. AHX was installed in a sodium test loop facility, STELLA (Sodium integral effect test loop for safety simulation and assessment) recently constructed at the KAERI site. The materials of the shell and tube in AHX are 304SS and 316SS, respectively. Evaluations of creep-fatigue damage based on 3D finite element analyses were conducted at several critical locations of AHX according to the recent elevated temperature design codes of ASME-NH and RCC-MR, and the evaluation results of the two codes were compared. Based on the high temperature damage evaluation, the AHX design has been finalized, and fabrication of the component was conducted.